Year	Percent
1991	77.618
1992	77.538
1993	77.407
1994	77.172
1995	76.81
1996	76.628
1997	76.375
1998	76.482
1999	76.231
2000	75.853
2001	75.614
2002	75.386
2003	75.14
2004	74.849
2005	74.529
2006	74.296
2007	74.063
2008	73.845
2009	73.663
2010	73.513
2011	73.477
2012	73.527
2013	73.585
2014	73.59
2015	73.574
2016	73.642
2017	73.694
2018	73.735
2019	73.757
2020	73.757
2021	73.735
2022	73.696